Re: worst injury you've ever heard of/seen
Torn ACL during a judo shiai. Osoto Gari from opponent who hooked heel around my leg, and then hooked toes/dorsal surface of foot around the leg, too - wrapped up, when I tried to get out of the throw, my knee popped.
THEN the CHIEF REFEREE grabbed my leg and tried manipulating it.. He'd be sued for his backside now, but it was Canada in 1979. (also the rules don't let anyone 'treat' you nowadays)
DARN that hurt.
I've heard of people doing Tenkan movement on wrestling mats and leaving their big toe behind. Yuk.